The number of commercial Wi-Fi hotspots will grow by 47 percent worldwide to 143,700 in 2006, according to ABI Research.

Almost three-quarters of these sites - 74 percent - are found in North America and Europe, but the Asia Pacific region is growing very rapidly and will surpass both Europe and North America in the number of Wi-Fi hot spots by 2011, the firm states. Currently, Europe is the market leader right now with over 57,000 hotspots.

The firm also found that the number of Wi-Fi sessions per subscriber is growing, meaning that subscribers are lingering longer and spending more time doing their email and surfing the Internet.

Major drivers behind Wi-Fi hot spots are retail and hospitality establishments. Fast food chain McDonald's, for example, has Wi-Fi-enabled 17 percent of its 4,000 locations, ABI says.

And the hospitality industry deploys almost 40 thousand hotspots worldwide, the research firm claims, growing to more than 109,000 hot spots by 2010. Voice over Wi-Fi will become a very attractive choice for many major hotel chains, both for their guests and for their staff, ABI predicts.